HoloDust on 12 September 2015
Valve has changed how other devs make FPS games both times they've released HL (first time in good, 2nd in not so good way, IMO).
Although I think they became quite lazy, I still think they are only one that can make another HL that can compare with the first two...so no, I don't see any other dev being even remotely capable of pulling it off.
